1. Technical Field
This present application relates to an optoelectronic device, which is especially related to an electrode design of an optoelectronic device.
2. Description of the Related Art
The light radiation theory of light emitting diode (LED) is to generate light from the energy released by the recombination of the charge carriers between an n-type semiconductor and a p-type semiconductor. Because the light radiation theory of LED is different from the incandescent light which heats the filament, the LED is called a “cold” light source. Moreover, the LED is more sustainable, longevous, light and handy, and less power-consumption, therefore it is considered as an alternative light source for the illumination markets. The LED applies to various applications like the traffic signal, backlight module, street light, and medical instruments, and is gradually replacing the traditional lighting sources.
FIG. 1A shows the structure of a conventional light emitting device. As FIG. 1A shows, a light emitting device 100 which comprises a transparent substrate 10, a semiconductor stack 12 formed above the transparent substrate 10, and an electrode 14 formed above the semiconductor stack 12, wherein the semiconductor stack 12 comprises, from the top, a first conductive-type semiconductor layer 120, an active layer 122, and a second conductive-type semiconductor layer 124.
FIG. 1B shows the structure of a conventional light emitting device. As FIG. 1B shows, the light emitting device 100 comprises a transparent substrate 10, a semiconductor stack 12 formed above the transparent substrate 10, and an electrode 14 formed above the semiconductor stack 12, wherein the electrode 14 comprises a reflective electrode 141 and a diffusion barrier layer 142. The diffusion barrier may have some disadvantages concerning reflectivity. Therefore the light extraction efficiency of the light emitting device 100 is reduced.
Moreover, the light emitting device 100 may be further connected to other components in order to form a light emitting apparatus. FIG. 2 shows the structure of a conventional light emitting apparatus. As FIG. 2 shows, the light emitting apparatus 200 comprises a sub-mount 20 carrying at least an electrical circuit 202, a solder 22 formed above the sub-mount 20; wherein the light emitting device 100 is bonded to the sub-mount 20 and a substrate 10 of light emitting device 100 is electrically connected with the electric circuit 202 on the sub-mount 20 by the solder 22, and an electrical connection structure 24 that electrically connects the electrode 14 of the light emitting device 100 to the electric circuit 202 on the sub-mount 20, wherein the sub-mount 20 may be lead frame or large size mounting substrate in order to facilitate circuit design and heat dissipation.